1. Technical Field
The present invention relates to a novel transverse connector system for interconnecting a first and a second rod, which are in an approximately parallel relationship to each other. More particularly the present invention relates to a novel low profile transverse connector system having opposing ends, which are configured to be capable of being securely attached to a first rod or second rod with each end of the connector system being capable of independent multidirectional articulation. The present invention also relates to a multidirectional articulating transverse connector system, the length of which can be easily increased or decreased and locked or unlocked in the selected configuration as needed.
2. Background Art
Disease, the effects of aging, or physical trauma resulting in damage to the spine has been treated in many instances by fixation or stabilization of the effected vertebra. A wide variety of spinal fixation apparatuses have been employed in surgical procedures for correcting spinal injuries and the effects of spinal diseases. Many of these apparatuses commonly use a pair of longitudinal link rods running in a relative parallel relationship to each other and the spinal column. These rods are connected to coupling elements, which in turn are secured to the underlying vertebral bone by spinal bone fixation fasteners such as pedicle screws, hooks, and the like. The pair of longitudinal links can be held in position relative to one another by transverse connectors, also known as transverse bridge elements or cross-connectors.
As the technology of spinal surgery has developed and improved, each of the spinal fixation components has also undergone improvements and modifications to address the short-comings of conventional spinal appliances. The natural anatomical variations in the spinal column of a subject are such that implanted spinal rods while approximating a parallel relationship one to the other can vary from that parallel relationship considerably and in multiple planes. For this reason, any transverse connector used to attach the two rods to each other should not be of a rigid design without the ability to be re-configured as needed during the process of implanting and attaching to the two opposing rods. While some improvements have been made in the articulation and re-configuration operation of transverse connectors during the implantation and rod connection process, a continuing need exists to provide an improved multidirectional articulating transverse connector that can adapt to a wide variance in the contours of the spinal column. Further, a need exists to provide such a transverse connector that also has a low profile and a smooth contoured surface, thereby reducing the potentially negative impact of the implanted appliance on the overlying and surrounding soft tissue of the subject into which the appliance has been surgically implanted.
In addition to meeting the need of providing a multi-planar articulating transverse connector to securely connect the two opposing spinal rods together a requirement exists to provide a transverse connector that is capable of being easily adjusted to increase or decrease the length between the two opposing bone connection points to accommodate natural anatomical variances and once selected, to lock or unlock the device in the selected configuration.
Conventional efforts to meet this need have fallen short of the desired transverse connector configuration. For example, U.S. Pat. No. 6,554,832, issued to Shluzas, as best seen in FIGS. 2 and 4 of that patent, provides a transverse connector, which includes first and second connector members for connection to the respective first and second spinal rods. The two connector members are connected one to the other by a connecting rod, which can be withdrawn or extended in alignment with the longitudinal axis of the cross-connector for purpose of adjusting the length thereof. As shown in FIGS. 2 and 4 of the Shluzas patent, the articulation of the connecting members to align with the two opposing spinal rods is limited to a single, centrally disposed ball joint (50). Importantly, the pivoting movement of the Shluzas connector is limited to movement within the same horizontal plane relative to the longitudinal axis of the spinal column. Thus, while the device of Shluzas does permit some limited adjustment in length and azimuth of the device, it is configured to structurally prohibit any upward or downward movement in relation to the surface plane of the spinal column. That is, the elevation of one end of the Shluzas connector relative to the other end of the connector cannot be adjusted. Thus, while the Shulzas design does provide some flexibility in adapting the alignment of the transverse connector to the opposing spinal rods, it falls short of the greater degree of adaptability that could be obtained by a truly multi-planar transverse connector having multiple articulating points.
For reasons discussed above a continuing need exists for a transverse connector system that provides ease of operation by the surgeon to simultaneously adjust in multiple dimensions one spinal rod connecting end of the system in relation to the other spinal rod connecting end of the system and to provide a device having a very low profile and smooth contours for surfaces in contact with adjacent soft tissue.